In the manufacture of large steel U-bolts of the type, for example, used to secure a semi-trailer body to a wheel supported frame or to secure a leaf spring to a wheel supported axle, it is common to cut a long steel rod having a diameter, for example, between 3/8 inch and 1-1/4 inches into rod sections or shorter rods each of which is threaded along opposite end portions while the rod remains straight. The threaded straight rods are then successively inserted into a hydraulically or power operated rod bending machine which bends or cold-forms each rod around a U-shaped mandrel to produce a U-bolt.
In order to position each rod within the bending machine, the operator may use a tape measure to position the rod so that the mid-point of the rod is aligned with the center of the mandrel. This measuring operation requires significant time. Some bending machines are also equipped with an adjustable stop which is used for locating one end of each rod to position the rod properly within the bending machine. When rods of different lengths are successively formed into U-bolts, it is necessary to adjust the end stop according to the length of each rod. Sometimes it is necessary to adjust the end stop frequently since the rods are commonly bent in sets of two or four rods, and each set may have a different length.
It has been found that as a result of a machine operator making an inaccurate measurement of the length of a rod or an incorrect adjustment of the end stop, a number of straight rods are formed into U-bolts without having the center point of the straight rod aligned precisely with the center plane of the rod bending machine. As a result, the U-bolts are formed with one leg longer than the other, and frequently, the improperly bent U-bolts cannot be used and must be scrapped since the bolts cannot be restraightened and reformed.